Preparation And Property Of Crosslinked Alkaline Anion Exchange Membrane

Alkaline anion exchange membrane fell cell (AAEMFC) has attracted more and more attention because of the merit of low methanol permeability, convenient in water management, using non-noble metal catalyst. As the core units of AAEMFCs, Alkaline anion exchange membranes (AAEM) play the role of conducting ion and separating electrodes direct influencing the operation effect and working time of AAEMFCs. However, AAEMs’ conductivity and stability are far less than commercial membrane Nafion(?). The primary purpose of this research is to synthesis the cross-linked AAEM based on aminomethylate polyaryletherketone (PDAEK) with high conductivity, good mechanical property and well stability. Systematic research on varies properties are investigated in detail.First,2,2’-dimethylaminemethylene-4,4’-biphenol(DABP) was prepared by Mannich reaction of4,4’-biphenol, then polymerized with4,4’-difluoro diphenylmethanone(DFK) resulting in PDAEK containing aminomethyl groups. The results of1R and1H-NMR confirm the polymer’s structure.Second, cross-linked AAEM (HDB-CAAEM) was prepared through alkylation, cross-linking, membrane preparation and alkali exchange based on PDAEK with CH3I to react with aminomethyl groups turning them into quaternary ammonium groups and hexamethylene dibromide as cross-linking agent.IEC value of the actual value (2.03mmol/g) and theoretical value (2.09mmol/g) indicated that alkylation reaction had a high conversion rate. The influence of the amount of cross-linking agent on water uptake, swelling degree, conductivity was investigated in this part. The conductivity of A9was0.064S/cm at80℃and declined10%after immersing in2M KOH at60℃for240h. Dry membranes demonstrated good mechanical property and stable thermal property.Last, a new cross-linked composite alkaline anion exchange membrane (Cm-CAAEM) was prepared in this work. The animation reaction with CH3I to polyaryletherketone containing aminomethyl groups (PDAEK), blending with chloromethyl polymer (CMPPEK), and ion exchange in1M KOH, was performed successively, resulting in Cm-CAAEM. The results showed this cross-linking method greatly lower the swelling degree and water uptake. The conductivity and tensile stress of B4respectively reached0.041S/cm at80℃and60.67MPa which is much higher than Nafion-115. The swelling degree and water uptake of B4were7.22%and23.08%and the membrane also showed good integrated performance.